# Copyright 2013 OpenStack Foundation
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import uuid

from oslo_config import cfg
from oslo_log import log
from oslo_utils import timeutils
import six

from keystone import assignment
from keystone.common import controller
from keystone.common import dependency
from keystone.common import validation
from keystone import exception
from keystone.i18n import _
from keystone.models import token_model
from keystone import notifications
from keystone.openstack.common import versionutils
from keystone.trust import schema


CONF = cfg.CONF

LOG = log.getLogger(__name__)


def _trustor_trustee_only(trust, user_id):
    if (user_id != trust.get('trustee_user_id') and
            user_id != trust.get('trustor_user_id')):
                raise exception.Forbidden()


def _admin_trustor_only(context, trust, user_id):
    if user_id != trust.get('trustor_user_id') and not context['is_admin']:
        raise exception.Forbidden()


@dependency.requires('assignment_api', 'identity_api', 'role_api',
                     'token_provider_api', 'trust_api')
class TrustV3(controller.V3Controller):
    collection_name = "trusts"
    member_name = "trust"

    @classmethod
    def base_url(cls, context, path=None):
        """Construct a path and pass it to V3Controller.base_url method."""

        # NOTE(stevemar): Overriding path to /OS-TRUST/trusts so that
        # V3Controller.base_url handles setting the self link correctly.
        path = '/OS-TRUST/' + cls.collection_name
        return super(TrustV3, cls).base_url(context, path=path)

    def _get_user_id(self, context):
        if 'token_id' in context:
            token_id = context['token_id']
            token_data = self.token_provider_api.validate_token(token_id)
            token_ref = token_model.KeystoneToken(token_id=token_id,
                                                  token_data=token_data)
            return token_ref.user_id
        return None

    def get_trust(self, context, trust_id):
        user_id = self._get_user_id(context)
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        _trustor_trustee_only(trust, user_id)
        self._fill_in_roles(context, trust,
                            self.role_api.list_roles())
        return TrustV3.wrap_member(context, trust)

    def _fill_in_roles(self, context, trust, all_roles):
        if trust.get('expires_at') is not None:
            trust['expires_at'] = (timeutils.isotime
                                   (trust['expires_at'],
                                    subsecond=True))

        if 'roles' not in trust:
            trust['roles'] = []
        trust_full_roles = []
        for trust_role in trust['roles']:
            if isinstance(trust_role, six.string_types):
                trust_role = {'id': trust_role}
            matching_roles = [x for x in all_roles
                              if x['id'] == trust_role['id']]
            if matching_roles:
                full_role = assignment.controllers.RoleV3.wrap_member(
                    context, matching_roles[0])['role']
                trust_full_roles.append(full_role)
        trust['roles'] = trust_full_roles
        trust['roles_links'] = {
            'self': (self.base_url(context) + "/%s/roles" % trust['id']),
            'next': None,
            'previous': None}

    def _normalize_role_list(self, trust, all_roles):
        trust_roles = []
        all_role_names = {r['name']: r for r in all_roles}
        for role in trust.get('roles', []):
            if 'id' in role:
                trust_roles.append({'id': role['id']})
            elif 'name' in role:
                rolename = role['name']
                if rolename in all_role_names:
                    trust_roles.append({'id':
                                        all_role_names[rolename]['id']})
                else:
                    raise exception.RoleNotFound("role %s is not defined" %
                                                 rolename)
            else:
                raise exception.ValidationError(attribute='id or name',
                                                target='roles')
        return trust_roles

    @controller.protected()
    @validation.validated(schema.trust_create, 'trust')
    def create_trust(self, context, trust=None):
        """Create a new trust.

        The user creating the trust must be the trustor.

        """
        if not trust:
            raise exception.ValidationError(attribute='trust',
                                            target='request')

        auth_context = context.get('environment',
                                   {}).get('KEYSTONE_AUTH_CONTEXT', {})

        # Check if delegated via trust
        if auth_context.get('is_delegated_auth'):
            # Redelegation case
            src_trust_id = auth_context['trust_id']
            if not src_trust_id:
                raise exception.Forbidden(
                    _('Redelegation allowed for delegated by trust only'))

            redelegated_trust = self.trust_api.get_trust(src_trust_id)
        else:
            redelegated_trust = None

        if trust.get('project_id'):
            self._require_role(trust)
        self._require_user_is_trustor(context, trust)
        self._require_trustee_exists(trust['trustee_user_id'])
        all_roles = self.role_api.list_roles()
        # Normalize roles
        normalized_roles = self._normalize_role_list(trust, all_roles)
        trust['roles'] = normalized_roles
        self._require_trustor_has_role_in_project(trust)
        trust['expires_at'] = self._parse_expiration_date(
            trust.get('expires_at'))
        trust_id = uuid.uuid4().hex
        initiator = notifications._get_request_audit_info(context)
        new_trust = self.trust_api.create_trust(trust_id, trust,
                                                normalized_roles,
                                                redelegated_trust,
                                                initiator)
        self._fill_in_roles(context, new_trust, all_roles)
        return TrustV3.wrap_member(context, new_trust)

    def _require_trustee_exists(self, trustee_user_id):
        self.identity_api.get_user(trustee_user_id)

    def _require_user_is_trustor(self, context, trust):
        user_id = self._get_user_id(context)
        if user_id != trust.get('trustor_user_id'):
            raise exception.Forbidden(
                _("The authenticated user should match the trustor."))

    def _require_role(self, trust):
        if not trust.get('roles'):
            raise exception.Forbidden(
                _('At least one role should be specified.'))

    def _get_user_role(self, trust):
        if not self._attribute_is_empty(trust, 'project_id'):
            return self.assignment_api.get_roles_for_user_and_project(
                trust['trustor_user_id'], trust['project_id'])
        else:
            return []

    def _require_trustor_has_role_in_project(self, trust):
        user_roles = self._get_user_role(trust)
        for trust_role in trust['roles']:
            matching_roles = [x for x in user_roles
                              if x == trust_role['id']]
            if not matching_roles:
                raise exception.RoleNotFound(role_id=trust_role['id'])

    def _parse_expiration_date(self, expiration_date):
        if expiration_date is None:
            return None
        if not expiration_date.endswith('Z'):
            expiration_date += 'Z'
        try:
            return timeutils.parse_isotime(expiration_date)
        except ValueError:
            raise exception.ValidationTimeStampError()

    def _check_role_for_trust(self, context, trust_id, role_id):
        """Checks if a role has been assigned to a trust."""
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        user_id = self._get_user_id(context)
        _trustor_trustee_only(trust, user_id)
        if not any(role['id'] == role_id for role in trust['roles']):
            raise exception.RoleNotFound(role_id=role_id)

    @controller.protected()
    def list_trusts(self, context):
        query = context['query_string']
        trusts = []
        if not query:
            self.assert_admin(context)
            trusts += self.trust_api.list_trusts()
        if 'trustor_user_id' in query:
            user_id = query['trustor_user_id']
            calling_user_id = self._get_user_id(context)
            if user_id != calling_user_id:
                raise exception.Forbidden()
            trusts += (self.trust_api.
                       list_trusts_for_trustor(user_id))
        if 'trustee_user_id' in query:
            user_id = query['trustee_user_id']
            calling_user_id = self._get_user_id(context)
            if user_id != calling_user_id:
                raise exception.Forbidden()
            trusts += self.trust_api.list_trusts_for_trustee(user_id)
        for trust in trusts:
            # get_trust returns roles, list_trusts does not
            # It seems in some circumstances, roles does not
            # exist in the query response, so check first
            if 'roles' in trust:
                del trust['roles']
            if trust.get('expires_at') is not None:
                trust['expires_at'] = (timeutils.isotime
                                       (trust['expires_at'],
                                        subsecond=True))
        return TrustV3.wrap_collection(context, trusts)

    @controller.protected()
    def delete_trust(self, context, trust_id):
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)

        user_id = self._get_user_id(context)
        _admin_trustor_only(context, trust, user_id)
        initiator = notifications._get_request_audit_info(context)
        self.trust_api.delete_trust(trust_id, initiator)

    @controller.protected()
    def list_roles_for_trust(self, context, trust_id):
        trust = self.get_trust(context, trust_id)['trust']
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        user_id = self._get_user_id(context)
        _trustor_trustee_only(trust, user_id)
        return {'roles': trust['roles'],
                'links': trust['roles_links']}

    @versionutils.deprecated(
        versionutils.deprecated.KILO,
        remove_in=+2)
    def check_role_for_trust(self, context, trust_id, role_id):
        return self._check_role_for_trust(self, context, trust_id, role_id)

    @controller.protected()
    def get_role_for_trust(self, context, trust_id, role_id):
        """Get a role that has been assigned to a trust."""
        self._check_role_for_trust(context, trust_id, role_id)
        role = self.role_api.get_role(role_id)
        return assignment.controllers.RoleV3.wrap_member(context, role)
